Structure Therapeutics reports 16.3% weight loss at 44 weeks for aleniglipron

Structure Therapeutics reported that its experimental daily pill, aleniglipron, produced a placebo-adjusted average weight loss of 16.3% (39 pounds) at the 180 mg dose after 44 weeks in a Phase 2 study called ACCESS II ^[1]. A 240 mg dose came in close behind, at 16.0% (37 pounds) ^[1]. The company says these are the highest weight-loss numbers reported so far for an oral GLP-1 drug and are close to what injectable versions of the class have shown ^[1][2].

The ACCESS II trial enrolled 85 adults with obesity or overweight who had at least one weight-related health condition ^[1]. Participants started on 5 mg of aleniglipron or placebo and increased their dose every four weeks, eventually reaching target doses of 120 mg, 180 mg, or 240 mg ^[1]. At 44 weeks, average weight change from baseline was -13.6% for the 120 mg group, -15.3% for 180 mg, and -15.0% for 240 mg, compared with a 1.1% gain for placebo ^[1]. None of the dose groups showed signs of the weight loss leveling off ^[1].

A separate open-label extension study, which lets people who finished the original 36-week trial keep taking the drug, found continued weight loss up to 16.2% (40.5 pounds) at 56 weeks among patients on a 120 mg dose ^[1]. In a third study looking at body composition, patients who started on a lower 2.5 mg dose and slowly increased to 120 mg lost 6.8% of their body weight after a median follow-up of 20 weeks ^[1].

That lower starting dose appears to matter for how well people tolerate the drug. Across the interim data cuts, discontinuations due to side effects were 2.0% in the extension study and 3.4% in the body composition study when patients began at 2.5 mg, compared with higher dropout rates tied to a 5 mg starting dose used earlier in the program ^[1]. As with other GLP-1 drugs, the most common side effects during dose increases were nausea and vomiting ^[1]. Structure Therapeutics said more than 625 participants have now taken aleniglipron across its studies, with what it describes as a favorable safety record and no signs of effects outside the drug's intended target ^[1].

Why it matters for patients

Aleniglipron is still years from possible FDA approval and is not available to patients now. If the weight-loss and tolerability results seen in this study hold up in larger, longer trials, it could offer people an oral alternative to weekly injections like Wegovy, Ozempic, Zepbound, or Mounjaro, without giving up much on effectiveness ^[1]. Oral drugs can be easier for some people to take consistently and may reduce concerns some patients have about needles.

Still, this is Phase 2 data from a relatively small number of participants, and the FDA has not evaluated it. The company itself frames the 44-week results as needing confirmation in "larger, longer-term studies" through comments from the trial's steering committee chair ^[1]. Side effect and dropout rates so far are based on short follow-up periods, median 20 weeks in the newest interim analyses, so it is not yet known how tolerability holds up over the kind of multi-year use these drugs typically require ^[1].

What happens next

Structure Therapeutics held an end-of-Phase 2 meeting with the FDA in the second quarter of 2026 and received what it called positive feedback, including guidance to start Phase 3 trials at a 2.5 mg dose ^[2]. The company plans to begin Phase 3 testing in the third quarter of 2026 ^[2]. Additional data are expected from the open-label extension study in Q3 2026 and from the body composition and type 2 diabetes sub-studies in Q4 2026 ^[2]. Aleniglipron data are also scheduled for presentation at the American Diabetes Association's Scientific Sessions in June 2026 ^[1][2]. No date for a possible FDA approval decision has been set, since the drug has not yet entered late-stage trials ^[2].